A survey or hospitals with anesthesia residency training programs was undertaken to determine the frequency and types of complications encountered with the use of bulk supplies of oxygen and nitrous oxide. Of the responding hospitals, 98 per cent dispense oxygen from a central source and 80 per cent dispense nitrous oxide from a central source. Nearly a third of the hospitals responding reported the occurrence of serious or potentially serious accidents related to their bulk gas delivery systems. In three instances accidents resulted in patient deaths. More than half of the reported incidents were decreases in oxygen pipeline pressure, often resulting in insufficient delivery of oxygen for clinical use. Most complications related to pipeline accidents could have been prevented by observance of National Fire Protection Association regulations. Anesthesiologists should be familiar with these regulations and should understand the designs of gas delivery systems in their institutions.